Post on 16-Jan-2016
Typhoid Fever in Africa:
Emerging Flouroquinolone Resistance
S KARIUKI1,3, G REVATHI2, J MUYODI1, J MWITURIA1, A MUNYALO1, S MIRZA3, CA
HART3
1Centre for Microbiology Research, KEMRI, Kenya, 2Department of Medical
Microbiology, Kenyatta National Hospital, Kenya, 3Department of Medical
Microbiology and Genito-Urinary Medicine, Liverpool, UK.
Introduction
• Salmonella Typhi : cause >10 million cases, 600,000 deaths / year, mainly in developing countries.
• Comprise 8-10% of all Salmonella serotype isolations in Kenya.
• MDR S. Typhi increasingly reported in Africa; chloramphenicol, ampicillin or cotrimoxazole increasingly ineffective.
Methods
• Between 1999 – 2000: 140 S. Typhi from blood cultures of adults (104) and children (36).
• 3 different regions of the country.
Methods
• Identification by serotype and phage type
• Antibiotic susceptibility testing - MIC using
E-test method
• Plasmid isolation and in-vitro conjugation
tests
• Genomic DNA characterisation by PFGE
Methods PCR
• PCR of RepHI1A replicon, present in IncHI plasmids
• PCR of gyrA, gyrB, parC and parE genes within
QRDR
• Digestion with 5 U of Hinf I – determine HinfI
mutations in gyrA site
RESULTSAntimicrobial susceptibility
• Only 19/140 (13.7%) fully susceptible to all drugs tested.
• 82.3% were MDR Strains high MICs
• Ampicillin,chloramphenicol, tetracycline, (MICs > 256µg/ml), streptomycin (MIC > 1024µg/ml) and cotrimoxazole (MIC> 32µg/ml)
RESULTSMICs for Quinolones n=140
MICs (g/mL)
Mode Range
Non-MDR* S. Typhi Nalidixic Acid Ciprofloxacin MDR S. Typhi Nalidixic Acid Ciprofloxacin
2 0.016 8 0.25
1-4 0.016 – 0.032 8-16 0.25 – 0.38
RESULTSPhenotypes and Genotypes of S.
Typhi
S. Typhi No. of No. (%) with XbaI and SpeI PFGE patterns
From isolates raised QMICs No. (%) isolates
Pattern I Pattern 2
MDR Sensitive MDR Sensitive
KNH 105 47 (44.7) 42 (40) 13 (12) 47 (44.7) 3 (2.8)
Embu 32 16 (50) 20 (64) 0 9 (28.6) 3 (9.3)
Nakuru 3 3 (100) 0 0 3 (100) 0
RESULTSPCR of QRDR
• No resultant mutations observed after sequencing PCR products of high Quinolone MIC strains.
Plasmids
• Resistance encoded on a 110-kb self-transferable plasmid of incHI1 incompatibility group.
• Increase in MICs of the quinolones had not resulted from any significant mutation
Conclusions
• Prior to 1991, all S. Typhi were fully susceptible to Abs
• Resistance 1st seen 1992, at 25%
• 1997 at 68% steadily rising to 76% by 2002.
CONCLUSIONS
• Two main genotypes in circulation – both S and R strains.
• NalR and Cipro high MIC strains (47%) have 10X MIC of sensitive strains
• Rx failures already being observed even within sensitive MIC bracket.
References1. Kariuki S, Revathi G, Muyodi J, Mwituria J, Munyalo A, Mirza S, Hart CA.
Characterization of multidrug-resistant typhoid outbreaks in Kenya. J Clin Microbiol. 2004 Apr;42(4):1477-82.
2. Kariuki S, Gilks C, Revathi G, Hart CA. Genotypic analysis of multidrug-resistant
Salmonella enterica Serovar typhi, Kenya. Emerg Infect Dis. 2000 Nov-Dec;6(6):649-51
3. Kariuki S, Hart CA. Global aspects of antimicrobial-resistant enteric bacteria. Curr Opin Infect Dis. 2001 Oct;14(5):579-86.